The exact details of the Scimitar's construction are unclear. Shinzon's discovery of the thalaron technology could have included data on the Scimitar class's development, or he could have used the thalaron generator as a bargaining tool to gain information on the class. Shinzon did have support from elements of the Romulan Imperial Fleet, so there is also the possibility they supplied him with the designs and/or parts. There is even the possibility that the secret base was not Shinzon’s own place of operations but merely the secret facility the Romulans were using to construct the Scimitar class and that Shinzon's connections within the Imperial Fleet allowed him to become involved.

The Scimitar was the only ship of her class to be completed, as the necessity for such a super-weapon disappeared following the end of the Dominion War. Shinzon used the Scimitar to destroy the remaining unfinished Scimitar-class vessels to ensure that no one could oppose him. (TOSnovel: Captain's Blood)

With the road clear of other Scimitar-class opposition and the backing of powerful factions within the Imperial Fleet, Shinzon used the thalaron technology to wipe out the Imperial Senate and appointed himself Praetor of the Romulan Star Empire. With an overture of peace, he then lured the Federation starship USS Enterprise into Romulan space. His goal was to capture Federation Starfleet Captain Jean-Luc Picard, the Human from whom he had been cloned, in order to cure himself of a life-threatening illness before attacking Earth, the Federation capital planet, with the thalaron weapon. The plot failed, and Picard escaped with the knowledge of the Scimitar's existence and Shinzon’s plans to strike Earth. The Enterprise fled Romulan space to meet with a battle group in preparation for a strike against the Scimitar, but Shinzon was close behind and engaged the Enterprise in the Bassen Rift, where communications disruptions would prevent the Federation starship from calling for aid.

Aid still came, however, in the form of a pair of Romulan Mogai-class warbirds, under the command of Imperial Fleet Commander Donatra of the IRW Valdore, who had reacted with horror upon learning of Shinzon's genocidal plans. While the warbirds were quickly neutralized by the Scimitar, their presence and subsequent destruction gave the Enterprise some time. However, despite their efforts, the Enterprise was outgunned and on the verge of being crippled. In the hope of stopping the Scimitar, Picard resorted to ramming the vessel; the tactic delivered a powerful blow and took out the Scimitar's disruptors. In an act of desperation, Shinzon ordered the thalaron weapon be fired on the Enterprise in the hopes of killing all aboard.

Unwilling to let his crew be killed, Captain Picard beamed to the Scimitar in the hope of stopping Shinzon. Equally unwilling to let his captain be sacrificed, Lieutenant CommanderData traversed the vacuum of space in a rescue attempt. Aboard the Scimitar, Picard reached the bridge and quickly neutralized the Reman crew, but was forced into hand-to-hand combat with Shinzon, finally killing him. Data arrived on the bridge to find Picard somewhat dazed, and beamed him back to the Enterprise before sacrificing himself to destroy the Scimitar and save his crewmates. (TNGmovie & novelization: Star Trek Nemesis; WizKidsmodule: Attack Wing)